Abstract:

The invention relates to a method for producing compressed air and for
injecting the same in an internal combustion engine, in particular a
diesel motor, comprising an exhaust turbocharger. The method has the
following steps: determination of operating parameters of the internal
combustion engine to identify operating states of the internal combustion
engine; production of compressed air by the internal combustion engine
using the determined operating parameter in an operating state without
combustion and storage of the produced compressed air; and injection of
the stored compressed air into the combustion engine using the determined
operating parameter in an operating state with combustion of the internal
combustion engine in order to increase the pressure in an induction
cycle. The invention also relates to a corresponding device.

Claims:

1. A method for generating compressed air and blowing the compressed air
into an internal combustion engine having an exhaust gas turbocharger,
comprising the acts of:determining an operating state of the internal
combustion engine from at least one operating parameter of the internal
combustion engine;generating compressed air by the internal combustion
engine when it is determined that the operating state is an operating
state without combustion;storing the generated compressed air; andblowing
of the stored compressed air into the internal combustion engine when it
is determined that the operating state is a combustion operating state of
the internal combustion engine.

2. The method according to claim 1, the compressed air is generated by at
least one cylinder of the internal combustion engine to which no fuel is
fed in the operating state without combustion.

3. The method according to claim 2, wherein when the compressed air is
generated in the operating state of the internal combustion engine
without combustion, a cross section of an exhaust line is reduced by a
throttle device.

4. The method according to claim 2, wherein the compressed air is
generated by at least one additional cylinder of the internal combustion
engine.

5. The method according to claim 1, wherein the generated compressed air
is stored in a compressed air vessel via at least one controlled valve.

6. The method according to claim 1, wherein the stored compressed air is
blown in by controlled switching on of a blowing-in valve.

7. An apparatus for generating compressed air and blowing the compressed
air into internal combustion engine having an exhaust gas turbocharger,
comprising:a compressed air vessel for storing compressed air;at least
one valve arranged to connect an outlet of at least one cylinder of the
internal combustion engine to the compressed air vessel when the internal
combustion engine is in an operating state without combustion;a
blowing-in valve arranged to connect the compressed air vessel to an
intake line of the internal combustion engine and to blow in stored
compressed air when the internal combustion engine is in a operating
state of acceleration; anda control unit for acquiring at least one
operating parameter of the internal combustion engine, determining
operating states of the internal combustion engine, and for controlling
the at least one compressed air storage valve and the blowing in valve.

8. The apparatus according to claim 7, wherein an exhaust line of the
internal combustion engine is configured to be connected via a branching
valve to the compressed air vessel in the operating state of the internal
combustion engine without combustion.

9. The apparatus according to claim 7, further comprising:a water
separator, the water separator dewater the compressed air associated with
the compressed air vessel.

10. The apparatus according to claim 7, wherein the blowing-in valve is
connected via a gas feed device arranged in the intake line.

11. The apparatus according to claim 10, wherein the gas feed device is a
fresh gas line section of a device for supplying fresh air for the
controlled blowing in of compressed air.

[0002]The invention relates to a method and a device for generating
compressed air and blowing it into an internal combustion engine, in
particular a diesel engine, having an exhaust gas turbocharger.

[0003]Such internal combustion engines, for example piston engines such as
diesel engines, with an exhaust gas turbocharger have, for example, an
operating state during acceleration which is referred to as "turbo lag".
Here, when the throttle is opened the internal combustion engine does not
react with an increase in the rotational speed until after a certain
delay time during which exhaust gas energy is not available, i.e., is
sufficient exhaust gas pressure is not available to drive the exhaust gas
turbocharger, and therefore no compressed fresh gas is available. In
order to get around this "turbo lag", solutions have been proposed which
are described in laid-open German patent applications DE 10 2006 008 783
A1 and DE 10 2006 785 A1. In said documents, compressed air, for example
from a compressed air accumulator, is introduced into the intake line of
the internal combustion engine in a controlled fashion in order to cover
the fresh gas demand of the internal combustion engine when said demand
is increased. This is carried out by a component which is arranged in the
intake line between the compressor of the turbocharger and the intake
manifold and which has a compressed air port and a controlled flap. When
compressed air is fed in, the controlled flap is closed, with the result
that the compressed air does not flow into the compressor of the exhaust
gas turbocharger but rather flows directed into the intake line.

[0004]In engines with exhaust gas circulation, it is in addition desirable
that sufficient fresh air is still fed to the engine in addition to the
exhaust gas in order to avoid putting the dynamics of the engine at risk.
Here too, the exhaust gas turbocharger is capable of feeding sufficient
fresh air only if it is operated by a sufficient flow of exhaust gas. The
active blowing in of air is also capable of contributing significantly to
improving the engine dynamics here.

[0005]The compressed air which is necessary for the blowing in of air can
be made available by a compressed air brake system in vehicles with such
a system, for example in a separate compressed air vessel which is
separate from the brake system.

[0006]The blowing in of air in the case of vehicles which do not carry any
compressed air with them is problematic.

[0007]The engine itself can be configured as a compressed air generator,
which is the state of the art today. Systems are known which selectively
do not supply certain cylinders with fuel on a temporary basis and which
carry away the air which has been compressed by the piston in this way
into a reservoir vessel.

[0008]The object of the present invention is therefore to make available a
method and a device for generating compressed air and blowing it into an
internal combustion engine in which the above disadvantages are
eliminated or significantly reduced and further advantages are obtained.

[0009]A basic idea of the invention is to make a system combination which
is generated during operation of the internal combustion engine without
combustion and using this compressed air, which is then stored and used
again in a subsequent combustion mode for a more rapid increase in
pressure in an intake cycle.

[0010]This advantageously ensures that an over-run fuel cutoff mode of a
motor vehicle is utilized to thereby generate compressed air. This is
particularly advantageous when a compressed air brake system with all its
components is not present.

[0011]In the over-run fuel cutoff mode, which can be clearly determined
from the operating parameters of sensors which are frequently already
present in the vehicle or an engine controller which is present,
compressed air is generated by at least one cylinder of the internal
combustion engine to which fuel is not fed in the operating state without
combustion. This can only be a single cylinder which is provided, for
example, particularly for generating pressure and which can be added to
the circuit as an additional cylinder only when the internal combustion
engine is subjected to high loading. However, it is also possible for all
the cylinders to jointly compress only intake air without fuel, and said
air can then be extracted from a common exhaust line via a controlled
valve. In this case, the exhaust line can be constricted in cross section
by suitable means, for example a throttle valve such as an engine brake,
in order to achieve a greater air quantity yield.

[0012]The valve is controlled by a control unit which interacts with the
engine controller or sensors in order to open this extraction valve at
the correct time, which extraction valve then, when in the opened state,
produces a connection to a compressed air vessel in which the extracted,
generated compressed air is stored. The valve can also be connected only
when there is one cylinder and/or with all the cylinders, in order to
obtain a large possibility of variation in the quantities of generated
and stored compressed air.

[0013]The stored air is available for the controlled blowing into the next
acceleration process of the internal combustion engine. As long as all
the cylinders of the internal combustion engine are used to generate
compressed air, even brief over-run fuel cutoff phases of the vehicle in
which the internal combustion engine is installed may already be
sufficient to generate sufficient quantities of compressed air for the
blowing-in process.

[0014]In a repeating operating mode, that is to say over-run fuel cutoff
phases are followed by acceleration phases, and vice versa, the storage
of the compressed air is necessary only for a brief time. Here, it is not
required of the compressed air generating means that it must always make
available sufficient compressed air, as is the case, for example, in a
compressed air brake system. Specifically, the storage of the compressed
air for the blowing in of air does not have to be made as complex for
only a brief storage time as the storage of compressed air in a
compressed air brake system. In particular, it is possible to dispense
with the drying of air as long as the condensation water which is
produced is discharged from the reservoir vessel, for example by a water
separator. The internal combustion engine can advantageously basically be
supplied with non-dried air.

[0015]In a further embodiment, the gas feed device is a fresh gas line
section of a device for supplying fresh air for the controlled blowing in
of compressed air. Here, a combination of the advantages of the blowing
in of compressed air in terms of what is referred to as "turbo lag" as
well as those of improved exhaust gas circulation are obtained.

[0016]Other objects, advantages and novel features of the present
invention will become apparent from the following detailed description
when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]The FIGURE schematically illustrates an embodiment of the present
invention.

DETAILED DESCRIPTION

[0018]The FIGURE is a schematic illustration of an internal combustion
engine 2 with an exhaust gas turbocharger 3 and an inventive device 1 for
generating compressed air and blowing it in.

[0019]In the illustrated example, the internal combustion engine 2 is a
diesel engine with eight cylinders I to VIII, an intake line 9 and an
exhaust line 10. An air inlet 7 is connected via an air filter 11 to an
intake air preheating means 12 which is connected to a compressor 5 of
the exhaust gas turbocharger 3. This is adjoined by a gas feed device 13
which opens into the intake line 9. The compressor 5 of the exhaust gas
turbocharger 3 is coupled to an exhaust gas turbine 4 of the exhaust gas
turbocharger 3 via a coupling 6, for example a shaft. The exhaust gas
turbine 4 is arranged in the exhaust line 10 upstream of an exhaust gas
outlet 8 for the exhaust gas of the internal combustion engine 2, and is
driven by an exhaust gas flow.

[0020]The gas feed device 13 has here a port with a blowing-in valve 27
for feeding in stored compressed air from a compressed air vessel 14 via
a blowing-in line 14. The compressed air vessel 14 is connected to the
blowing-in line 24 via a water separator 19 for separating condensation
water from the compressed air.

[0021]The compressed air vessel 14 is fed via a collecting pressure line
23 which communicates here with an outlet of a pressure line valve 25 and
an outlet of a branching line valve 26. The pressure line valve 25 is
connected via a pressure line 21 to an outlet of the cylinder VIII of the
internal combustion engine 2, while the branching line valve 26
communicates via a branching pressure line 22 with the exhaust line of
the cylinders I to VII. The cylinder VIII is embodied here as an
additional cylinder which is connected via a suction line 20 to the
intake line 9 and can only be provided for generating compressed air.
However, in the event of particular loading of the internal combustion
engine 2 it can also be connected into the circuit as a working cylinder
in addition to the other cylinders I to VII, and it can be provided with
fuel. In this case, its outlet is also connected to the exhaust line 10
(not shown here), as can easily be imagined.

[0022]An engine control device (not shown) is connected to injection
systems of the cylinders I to VIII. The engine control device controls
the internal combustion engine in a known fashion and is not explained
further.

[0023]The gas feed device 13 is in this example a fresh gas line section
such as is described in German patent documents DE 10 2006 008 783 A1 and
DE 10 2006 008 785 A1 in conjunction with an associated compressed air
generating means. A detailed explanation is therefore not given here.

[0024]The function of this device 1 will now be described.

[0025]A control unit 28 acquires, through comparison with previously
defined threshold values, the operating states of the internal combustion
engine 2 from data values of the engine control device or from a bus
device, for example. If an over-run fuel cutoff mode is present, fuel is
not fed into the cylinders I to VIII and now they suck in and compress
only air from the intake line 9. In the expulsion cycle, the branching
line valve 26 and also the pressure line valve 25 are opened by the
control unit 28 and the compressed air which is generated is fed into the
compressed air vessel 14 via the collecting pressure line 23. In the
other cycles of the internal combustion engine 2, the valves 25 and 26
remain closed. The compressed air vessel 14 can be provided, in a
conventional way which is not illustrated in more detail, with a
non-return valve which prevents the compressed air stored in it from
being able to escape.

[0026]At the start of an acceleration state of the internal combustion
engine 2, which is acquired by means of the connection of the control
unit 28 which is explained above, said control unit 28 opens the
blowing-in valve 27 at a suitable time in the intake cycle of the
cylinders I to VIII in order therefore to bring about an increase in
pressure through the stored compressed air from the compressed air vessel
14.

[0027]The invention is not restricted to the exemplary embodiments
described above. For example, it can be modified within the scope of the
appended claims.

[0028]It is therefore conceivable, for example, that the compressed air
vessel 14 is fed by a second compressed air generating source which is
equipped here in the form of a compressor 15 with a drive 16 which can,
for example, be an electric motor. The compressor 15 is connected by a
compressor suction line 17 to the atmosphere. Its pressure side is
connected to the compressed air vessel 14 via a compressor pressure line
18 and a non-return valve (not shown). With this compressor 15 it may be
possible, for example, before the internal combustion engine 2 starts, to
fill the compressed air vessel 18 with compressed air to such an extent
that the stored compressed air has an assisting effect when the internal
combustion engine 2 starts.

[0029]For example, this compressor 15 can also be representative of a
compressed air generating system or an additional system which is present
in a utility vehicle.

[0030]The valves can also be controlled pneumatically or
electro-pneumatically.

[0031]The gas feed device 13 can be a fresh gas line section of the
compressed air device described in German patent documents DE 10 2006 008
783 A1 and DE 10 2006 008 785 A1 and can be coupled to it.

[0032]The foregoing disclosure has been set forth merely to illustrate the
invention and is not intended to be limiting. Since modifications of the
disclosed embodiments incorporating the spirit and substance of the
invention may occur to persons skilled in the art, the invention should
be construed to include everything within the scope of the appended
claims and equivalents thereof.